Estimation of hydrodynamical model parameters from the invariant spectrum and the Bose-Einstein correlations of π- mesons produced in (π+/K+)p interactions at 250 GeV/c

The invariant spectra of pi(-) mesons produced in (pi(+)/K+)p interactions at 250 GeV/c are analysed in the framework of the hydrodynamical model of three-dimensionally expanding cylindrically symmetric, finite systems. A satisfactory description of experimental data is achieved. The data favour the pattern according to which the hadron matter undergoes predominantly longitudinal expansion and non-relativistic transverse expansion with mean transverse velocity [u(t)] = 0.20 +/- 0.07, and is characterized by a large temperature inhomogeneity in the transverse direction: the extracted freeze-out temperature at the center of the tube and at the transverse rms radius are 140 +/- 3 MeV and 82 +/- 7 MeV, respectively. The width of the (longitudinal) space-time rapidity distribution of the pion source is found to be Delta eta = 1.36 +/- 0.02. Combining this estimate with results of the Bose-Einstein correlation analysis in the same experiment, one extracts a mean freeze-out time of the source of [tau(f)] = 1.4 +/- 0.1 fm/c aad its transverse geometrical rms radius, R-G(rms)= 1.2 +/- 0.2 fm. (C) 1998 Elsevier Science B.V.